Begin with bar on back and front foot on box
Using only front leg, drive up onto box until leg is straight
Forcefully drive back leg up until knee is at waist level
Carlisle’s Comments: The game of football consists of many one legged movements. If one of your legs is capable of running a 4.5 and the other leg can only run a 4.8, then you will run a 4.8. The single-leg nature of this exercise helps you overcome such deficiencies and develop strength equally on both sides.
This movement also develops explosion, proprioception and core strength, because you have to balance on one leg. It mimics proper running form with the toe up-knee up action. Picture a D-end or anyone else in his football stanceone leg is ahead of the other. It is clear to see how this applies to the game.